1. Field of Invention
This invention relates to a hot water system which uses the cold and hot water recirculation to provide a fast hot water supply and avoid the waste of water.
2. Related Art
Conventional domestic hot water supply system uses a water heater to heat up the water from the cold water pipes, and flows to the fixtures through hot water pipes, such as the faucets in the bathroom or kitchen. When using the hot water at the first time, there is a lot of cold water in the hot water pipes, the user has to open the faucet and drain the cold water before he gets the hot water. The user has to wait and the water is wasted. As for this water wasting problem, there are many inventions designed to solve this problem.
One of the most common hot water recirculation system at present time uses a pump installed under the sink, the pump inlet is connected to the hot water pipe under the sink, and its outlet is connected to the cold water pipe, the user has to push a start button to start the pump, and the cold water in the hot water pipes will be pumped into the cold water pipes and start the recirculation, when the recirculated water is heated by the water heater and returns to the pump through the hot water pipes, on the detection of a rising of water temperature, the pump will be stopped, and the user can now open the faucet and use the hot water. An example product is provided by the Dux Manufacturing Limited called READYHOT. But this kind of solution must install a pump under every sink that needs fast hot water, and for a shower room faucet there are problems in installation space and in the power supply safety.
There are other more complicated hot water supply systems, but most of them require the installation of a complicated control valves (for example, the U.S. Pat. No. 7,140,382), and some have to change the piping system layout (for example, U.S. Pat. No. 6,895,985 and U.S. Pat. No. 5,918,625). These solutions are basically not particle for an already built house.